WiFi & 4G Speeds - how fast should they be?

I am in a 4g area. When I was at the AT&T store the sales rep pulled out his phone and used the speed test app and his phone was hitting 30 Mbps. I think he had a Iphone. I pulled out my Samsung Note and was hitting 9 to 10.

How fast should a phone be on 4G?
How fast should the phone be on WiFi ?

Now for my results this morning:

My desktop PC = 52 Mbps

Lumia 1520:
WiFi - most of the time its around 5 or 6 Mbps down. On occasions it hits 12Mps down and up varies alot.
4G - 4.9 Mbps down and .53 Mbps up

depends on a lot of things, especially your data plan for del and mobile. Additionally, your router is able to have an order for connected devices, maybe your wife's galaxy is on top of that list and gets the full bandwidth then, if you're below you'll only get the "rest". I also have varying speeds, my TV only gets 20, my phone 39 and my laptop 49, but via cable. Also, did you test the devices at the same position?
I don't have a 1520 myself, but since it uses the Snapdragon 800 as SoC it should work just as the current Android devices, which have no problems so far.. maybe check another wifi network, but if you get way lower speeds with the same networks there might be something wrong..

Are you using the Speedtest.net app? Or are you using Network Speed Test by MS Research? I too get below average speeds on LTE and WiFi on both. Network Speed Test seems a little more accurate though (higher).